1. Field
The present general inventive concept relates to a toner to develop an electrostatic charge image, a device to supply the toner, and an apparatus and method to form an image using the toner.
2. Description of the Related Art
Methods of preparing toner particles suitable to use in an electrophotographic process and an electrostatic image recording process may generally be classified into a pulverization method and a polymerization method.
Conventionally, toners used for image-forming apparatuses are mainly prepared through the pulverization method. Since the precise control of toner particle size, narrow particle size distribution, and toner shape is difficult in terms of the pulverization method, it is difficult to independently design each important property required for a toner such as charging, fixation, fluidity, or storage ability.
Thus, a polymerized toner has gained attention because controlling a particle diameter is facilitated and a complex manufacturing process such as classification is unnecessary. When a toner is prepared by using the polymerization method, a polymerized toner having a desired particle diameter and particle size distribution may be obtained without pulverizing or classification. Since a toner prepared using the polymerization method has a smaller particle diameter and a narrower particle size distribution than those of a toner prepared using the pulverization method, the polymerized toner has advantages such as improved image quality, including increased charging and transfer efficiency, broad fixing latitude, improved dot and line reproducibility, reduced toner consumption, and improved gloss properties. As an example of a method of preparing a toner by polymerization, an aggregation process has been proposed which may be performed in such a way that a binder resin, a colorant, a releasing agent, and the like are prepared in a form of particulates and an aggregation process using a metal salt is then performed thereon to control a toner particle size and shape thereof. This aggregation process allows control of a toner particle size and toner particle size distribution with reproducibility, and thus, this process has a practical use. For example, U.S. Pat. No. 6,268,102 relates to a process for the preparation of a toner which comprises mixing a colorant, a latex resin, a wax, and a polyaluminum sulfosilicate coagulant.
Even when the aggregation process is used, however, the process is still insufficient to uniformly control a toner particle size and a shape of toner particles. That is, in toner particle size distribution, when the diameters of toner particles are in a range that is greater than an average particle diameter, the shape of the toner particles can be controlled pretty well. On the other hand, when the toner particle diameters are in a range that is less than the average particle diameter, the shape of toner particles becomes approximately spherical, such that problems related to blade cleaning properties in an electrophotographic process may occur.
In particular, a toner used in a one-component contact development type image forming apparatus needs to have good blade cleaning properties.
A one-component contact development method is performed by forming a toner thin layer on a developing roller made of conductive rubber by using a blade and then contacting the developing roller with a photoreceptor to develop an electrostatic latent image formed on the photoreceptor. In this process, toner particles can be transferred to even a weak electric field region of a latent image so that minimized dot reproducibility and clear color reproducibility are facilitated. Thus, in such a one-component contact development method, a high-quality image can be obtained even with an apparatus having a simple structure. In this one-component contact development method, however, a blade is required to be firmly pressed against a surface to charge a toner on a developing roller. In addition, a photoreceptor and a developing roller contact each other, and thus, a driving torque increases as compared to a two-component development method. Moreover, toner particles may be fused on a blade so that an image defect and a charging defect are likely to occur.
As described above, in a one-component contact development method, as compared to a non-contact development method, the stress applied to the toner particles is increased due to contact between a photoreceptor and a developing roller. Thus, if the toner does not have durability with respect to such a circumstance, the toner particles are fused on the photoreceptor and the developing roller, causing contamination of an image forming apparatus and resulting in image defects.